Centrifugal clamp



April 4, 1944. L. B. BERG 2,345,786 CENTRIFUGAL 'cLAMP Filed Dec. 4, 1941 2 Sheets-Sheet 1 loads \5? 3e?" i f dz April 4, 1944. I, B. BE 2,345,786

CENTRIFUGAL CLAMP Patented Apr. 4, 1944 CENTRIFUGAL CLAMP Louis B. Berg, Chicago, Ill., assignor to Borg- Warner Corporation, Chicago, 111., a corporation of Illinois Application December 4, 1941, Serial No. 421,613

2 Claims.

This invention relates to a clamping device for clamping a blank against a spinning form. The invention will be described with reference to its application to a disc rolling machine, but it is to be understood that the invention is of greater scope and is not to be limited to such application.

It has been proposed to form a centrally apertured blank for a wheel body or the like by rolling and spinning a heated circular -blank radially inwardly from an intermediate diameter to decrease the size of the central opening which had been previously formed therein and to decrease the thickness of the central portion of the blank. In order for the rolling operation to be performed in a minimum amount of time, it is necessary to complete the rolling operation in one step to avoid repeated handling of the blank. This requires that the blank be rotated at a relatively high speed and also that rather large pressures be exerted upon the blank during the rolling and spinning operation. The radial inward forces developed by the roll as it contacts and works the blank become very large and the blank must therefore bersecurely clamped to the spinning form if it is to withstand such radial forces. Since the rolling is done toward the center, it becomes inexpedient to attempt to clamp the blank to the spinning form at its center as would normally be the case. The clamp therefore must be placed at or near the outer periphery of the blank.

I have found that when a clamp of the usual ring type is used at the outer periphery of a spinning form, the centrifugal force developed in the clamp as a result of the rotation of the form becomes large enough to expand the clamp and render it ineffective to hold the blank on the form. Thus when such a clamp is used, insufficient resistance to radial inward movement of the blank is'developed at high speed to retain the blank on the form, and as a consequence the blank is moved bodily relative to the form with a resulting destruction of the blank and, which is still more serious, with great danger of injury to the operator.

The principal object of this invention is to provide a. clamp for a blank which is to be worked while rotated, said clamp being most efiective under the conditions existing at the time the blank is to be worked.

Another object of this invention is to provide a clamp for a spinning object, the efficiency of the clamp being a function of the speed of rotation of the blank, such that radial forces, either toward or away from the center of the blank, will be resisted.

These and other objects and features of this invention will become apparent from the following detailed description when taken together with the accompanying drawings in which:

Fig. 1 is a fragmentary elevation, partly in section, of a disc rolling machine to which this invention may be applied;

Fig. 2 is a fragmentary plan View, partly in section, of the apparatus of Fig. 1 taken along lines 22 thereof; and

Fig. 3 is a fragmentary elevation in section of the clamp showing the clamp in released position.

Referring now to the drawings for a detailed description of the invention, the machine illustrated is comprised of a platform I E] which is adapted to be rotated by any suitable means such as a pulley 30 and a rope drive 3| from a prime mover (not shown). A platen II is mounted on platform I0 and is providedwith a central shaft i2 which is slidably retained in rotatable platform 10. A friction clutch connection I3 is provided between platform It) and platen ll whereby to drive the latter from the former. Said platen H may be raised or lowered relative to platform ill by any suitable means, such for example as a lever I 4 riding on a cam l5 and operated by an external control l6 which may be in the form of a piston and cylinder. Obviously, any other suitable means for raising and lowering platen ll may be substituted for the lever and control disclosed.

A frame I! straddles platen II and supports a crank shaft and a connecting rod (not shown) which are used to raise and lower a slide 20. The

details of the crank shaft and connecting rod are disclosed in a copending application of A. Doderer, Serial No. 419,280, filed November 15, 1941, and hence will not be described herein. Said slide 20 supports a roll carriage 2! in which is rotatably mounted a roll 22 for operating against or upon a blank 23 which may be mounted upon platen ll. Said carriage 2| is bolted to a plate 24 which is slidably supported from slide stop blocks 28 formed in frame ll, said blocks contacting adjustable blocks 29 in slide 20.

In the form selected for illustrating this: invention, blank 23 is comprised of a fiat central section 32 and a conical tapered section 33, platen ll being suitably formed to receive a blank so shaped. Blank 23 further is provided with an aperture 34 located centrally thereof, said aperture being of greater diameter initially than the central opening in the finished blank. It is contemplated that the central fiat section 32 of the blank will be rolled and spun radially inwardly in the machine illustrated, to decrease the size of the central opening and to work the. metal so rolled and spun toa, denser and more.

homogeneous grain structure.

In order to assist in centering the blank on platen H, said platen H is provided with a central opening 35 into which is adapted to be inserted a pin 36 extending downwardly from a conical disc 31. Said disc 3'? is in turn connected to a piston rod 38 which is operated by a hydraulic cylinder 39 secured to plate 24' so as to be movable laterally therewith. Blank 23 will be approximately centered on platen I l by virtue of the inherent centering effect produced by the conical portion 33 as it settles over platen H. Final centering is accomplished by lowering conical plate 3'1 until it contacts the edges of aperture 361. Since pin 35 is accurately aligned with aperture 35, conical plate 3? will likewise be accurately aligned with platen H and, except for irregularities which might exist in the aperture 34, blank 23 will therefore be accurately centered upon platen H. It is contemplated that plate 3? and its associated pin 35 will be raised completely from platen H and blank 23 during the rolling operation so as not to interfere with lateral movement of roll 22 across the surface of the blank.

It will be apparent thus far that unless blank 23 is securely clamped to platen ll by a peripheralclamp, roll 22, as it moves acrossthe blank, will tend to draw the blank over the surface of platen ll, thereby destroying the concentric relation between the platen and blank and rendering impossible the successful rolling-in. of the central portion 32 Furthermore, should the blank. become eccentric to the platen, large unbalanced, forces will be developed which will tend to eject the spinning blank from the machine,

thereby endangering the life of the-operator. To

avoid such a contingency the novel apparatus hereinafter. described is employed.

The required clamping action is obtained by means of a plurality of individual clamps 40" which are secured to the periphery of platen H at spaced intervals as shownin Fig. 2. Platen, II is providedwith pairs of lugs 4| Whichare- 42 to hold blank 23 upon the platendespite any:

Clamps 4i? inturn are comprised:

It is of platen H from platform It breaks the fric' tion. connection l3 and permits platen H to be held against rotation. The platen may thus be brought to restbefore the clamp is released and the blank removed with safety. Weights 43 first strike the corner 46 of a guard 41 which is fixed to frame l1 against relative movement therewith. The continued vertical movement of platen II causes clamp 40 to rotate about its pin 42- to the position shown wherein finger 44 is removedfrom the surface of the blank beyond the greatest radius of the blank.

It is understood that the foregoing description is merely illustrative of a preferred embodiment of the invention and that the scope of the invention, therefore, is not to be limited thereto, but is to be determined by the appended claims.

I claim:

1'. A rolling machine for rolling and spinning a circular blank against a rotating form, said iorm comprising a central iiat section and a conical section adapted'to accommodate corresponding fiat and conical sections in the blank, the rolling operation being performed by a radially inward movement of a roll against the flat section such that radial inward forces are developed in the blank, a plurality of fingers disposed at the outer periphery of the conical section and adapted to contact the outer periphery of the blank, said fingers at no time extending into the plane of the flat section, thereby avoiding inter,- ference with theroll, and means responsive to centrifugal force developed as a result of the rotation ofthe form for operating the fingers to clamp. the blank against the form, said means providinga clamping force for the fingers which is. proportional to the square of the speed of rotation of the spinning form, such that the clamping force exceeding the radial force developed as a result of the rolling operation.

2. A rolling machine for operating upon a circular blank. against a rotating form, said form including a flat section to accommodate a flat section in the blank, the rolling operationbeing performed by a radially. inward movement of a.

roll. against the flat section such that radial inward forces are developed in the blank, and

means for holding the blank upon the form, said last-mentioned means comprising pairs of lugs symmetrically disposed about the periphery of the form, and clamps pivotally supported by said. pairsoflugs; said clamps.comprisingfingers rotatable to a position over the blank, and centrifugal weights formed integrally with. the fingers. and disposed on. the side, of the; lugs .op1-

posite: the fingers such' that when. the form,1is.

rotated. a centrifugal force will be developedin the weights which will act in a direction toforce the'fingers against the blank and the form.

LOUIS B. BERG. 

